SAN FRANCISCO -- A man wearing a shirt slamming the San Francisco 49ers was seriously wounded as gunfire erupted in the parking lot after the team's NFL preseason game, while another man sustained lesser injuries in an earlier shooting, police said.

The violence occurred after the 49ers' 17-3 victory Saturday night over the Oakland Raiders at Candlestick Park, police Sgt. Michael Andraychak said.

A 24-year-old man was treated at San Francisco General Hospital for life-threatening injuries, and a 20-year-old man was hospitalized with less serious wounds, Andraychack told The Associated Press.

The violence comes months after a San Francisco Giants fan was severely beaten by two men in Los Angeles Dodgers gear outside Dodger Stadium after the teams' season opener March 31. Two suspects have been charged in the case.

Police Sgt. Frank Harrell said that in Saturday's attack the 24-year-old man, who was wearing a T-shirt referring to the 49ers with an obscenity, was shot two to four times in the stomach, according to reports in the Oakland Tribune and the San Francisco Chronicle. He drove his truck to a gate and stumbled to security, Harrell said.

The other man was shot before that in the parking lot and had superficial face injuries, Harrell said.

"We are treating it as separate shootings, but we believe they are related," Harrell told reporters outside the stadium.

Harrell said police took a man in a Raiders jersey off a party bus before it left the stadium and were calling him a suspect.

The suspect and the two victims had all attended the game, Harrell told the newspapers.

The 49ers issued a statement acknowledging the shootings and the investigation, but offering no further details.

In violence during the game, the Oakland Tribune reported that a 26-year-old San Rafael man was assaulted and knocked unconscious in a men's restroom. Police said he was hospitalized and a suspect was arrested. There was no immediate indication that it was connected to the postgame shootings.

In the Giants fan attack in March, the two men accused in the beating, Louie Sanchez, 28, and Marvin Norwood, 30, have pleaded not guilty.

Bryan Stow, a Santa Cruz paramedic, suffered severe brain injuries and remains hospitalized.

Stow's doctor said this month that he has made "significant improvement" despite a series of ups and downs since his near-fatal attack. He said Stow is awake, breathing on his own, can move slightly and has been able to interact with his family.

The attack drew widespread attention and focusing the spotlight on security at Dodger Stadium, and the intense rivalry among Dodgers and Giants fans.